U.S. patent application number 14/195982 was filed with the patent office on 2014-09-18 for heat transfer surface with nested tabs.
This patent application is currently assigned to Dana Canada Corporation. The applicant listed for this patent is Dana Canada Corporation. Invention is credited to Michael Bardeleben, Andrew Buckrell.
Application Number | 20140262170 14/195982 |
Document ID | / |
Family ID | 51522223 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140262170 |
Kind Code |
A1 |
Buckrell; Andrew ; et
al. |
September 18, 2014 |
Heat Transfer Surface With Nested Tabs
Abstract
A heat transfer surface and a heat exchanger comprising the heat
transfer surface are disclosed, the heat transfer surface
comprising a corrugated member having parallel spaced apart ridges
and planar fin surfaces extending therebetween. The planar fins
surfaces comprise tabs formed in the surface thereof for forming
counter-rotating vortices in the fluid flowing over the heat
transfer surface, the tabs being lifted out of the surface of the
planar fin surface and extending into or nesting within the
openings formed by the corresponding tabs in the adjacent planar
fin surface so as to achieve high fin density.
Inventors: |
Buckrell; Andrew;
(Kitchener, CA) ; Bardeleben; Michael; (Oakville,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dana Canada Corporation |
Oakville |
|
CA |
|
|
Assignee: |
Dana Canada Corporation
Oakville
CA
|
Family ID: |
51522223 |
Appl. No.: |
14/195982 |
Filed: |
March 4, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61787261 |
Mar 15, 2013 |
|
|
|
Current U.S.
Class: |
165/151 |
Current CPC
Class: |
B21D 53/085 20130101;
F28F 1/128 20130101; F28D 1/0375 20130101; F28F 1/325 20130101;
F28F 3/027 20130101; F28D 1/0333 20130101 |
Class at
Publication: |
165/151 |
International
Class: |
F28F 1/10 20060101
F28F001/10 |
Claims
1. A heat transfer surface for a heat exchanger comprising: a
corrugated member having a plurality of parallel, spaced apart
upper and lower ridges and planar fin surfaces extending
therebetween; each corrugation of said corrugated member comprising
either an upper or lower ridge and two planar fin surfaces
extending in the same direction from the corresponding upper or
lower ridge; the planar fin surfaces being formed with a plurality
of spaced apart tabs, each tab having an attached base and a free
end projecting out of the plane of the corresponding planar fin
surface; a plurality of openings formed in the planar fin surfaces,
the plurality of openings formed by the tabs projecting out of the
planar fin surface; wherein the free ends of the tabs formed in one
of the planar fin surfaces extend into the openings formed in an
adjacent planar fin surface.
2. The heat transfer surface as claimed in claim 1, wherein the
free end of the tabs is oriented upstream from the attached
base.
3. The heat transfer surface as claimed in claim 2, wherein the
planar fin surfaces are formed with a plurality of rows of spaced
apart tabs, the rows extending along the length of the planar fin
surface.
4. The heat transfer surface as claimed in claim 3, wherein
adjacent rows of spaced apart tabs are staggered with respect to
one another.
5. The heat transfer surface as claimed in claim 3, wherein the
rows of spaced apart tabs are arranged in a cascading pattern.
6. The heat transfer surface as claimed in claim 1, wherein the
free ends of the tabs formed in one planar fin surface project out
of the plane of the planar fin surface in a first direction, the
free ends of the tabs formed in an adjacent planar fin surface
projecting out of the plane of the planar fin surface in the same
first direction.
7. The heat transfer surface as claimed in claim 3, wherein the
rows of spaced apart tabs each comprise a first set of tabs that
project out of the plane of the planar fin surface in a first
direction and a second set of tabs that project out of the planar
fin surface in a second direction.
8. The heat transfer surface as claimed in claim 1, wherein each
planar fin surface comprises a first portion wherein the tabs are
formed with their free end oriented upstream from the attached
base, and a second portion wherein the tabs are formed with their
free end oriented downstream from the attached base.
9. The heat transfer surface as claimed in claim 1, wherein each
planar fin surface comprises a first portion wherein the tabs are
formed with their free end oriented upstream from the attached base
and at least a second portion wherein the tabs are formed with
their free end oriented downstream from the attached base, wherein
the first portion and the second portion are formed in an
alternating pattern along the length of the planar fin surface.
10. The heat transfer surface as claimed in claim 8, wherein the
tabs in first and second portions have varying size.
11. The heat transfer surface a claimed in claim 8, wherein the
tabs in the first and second portions are arranged at varying
angles with respect to the direction of incoming flow.
12. The heat transfer surface as claimed in claim 1, further
comprising flow accelerating features formed in the planar fin
surface intermediate the spaced-apart tabs, wherein the flow
accelerating features comprise rounded protrusions formed between
the spaced apart tabs proximal to the attached base.
13. The heat transfer surface as claimed in claim 1, wherein the
tabs are triangular tabs, the triangular tabs having a tip in the
form of said free end, the tip being oriented upstream from the
attached base at an angle to the incoming flow.
14. The heat transfer surface as claimed in claim 1, wherein the
planar fin surfaces are one of the following alternatives: parallel
to one another or inclined with respect to one another.
15. The heat transfer surface as claimed in claim 1, wherein the
upper and lower ridges are one of the following alternatives:
rounded or generally flat surfaces.
16. A heat exchanger comprising: a plurality of stacked tubular
members extending in spaced apart generally parallel relationship;
a first set of fluid flow passages defined by said plurality of
stacked tubular members; a second set of fluid flow passages formed
between adjacent tubular members; a pair of inlet and outlet
manifolds in communication with said first set of fluid flow
passages; a plurality of heat transfer surfaces disposed in said
second set of fluid passages between adjacent tubular members; each
of said heat transfer surfaces comprising: a corrugated member
having a plurality of parallel, spaced apart upper and lower ridges
and planar fin surfaces extending therebetween; each corrugation of
said corrugated member comprising either an upper or lower ridge
and two planar fin surfaces extending in the same direction from
the corresponding upper or lower ridge; the planar fin surfaces
being formed with a plurality of spaced apart tabs, each tab having
an attached base and a free end projecting out of the plane of the
corresponding planar fin surface; a plurality of openings formed in
the planar fin surfaces, the plurality of openings formed by the
tabs projecting out of the planar fin surface; the free ends of the
tabs formed in one of the planar fin surfaces extending into the
openings formed in an adjacent planar fin surface.
17. The heat exchanger as claimed in claim 16, wherein the tabs are
triangular tabs, the triangular tabs having a tip in the form of
said free end, the tip being oriented upstream from the attached
base.
18. The heat exchanger as claimed in claim 16, wherein the heat
transfer surface is bi-directional such that each planar fin
surface comprises a first portion wherein the tabs are formed with
their free end oriented upstream from the attached base, and a
second portion wherein the tabs are formed with their free end
oriented downstream from the attached base.
19. The heat exchanger as claimed in claim 16, wherein the planar
fin surfaces are formed with a plurality of rows of spaced apart
tabs, the rows extending along the length of the planar fin
surface; and wherein the rows of spaced apart tabs each comprise a
first set of tabs that project out of the plane of the planar fin
surface in a first direction and a second set of tabs that project
out of the planar fin surface in a second direction thereby forming
an alternating pattern along the length of the planar fin
surface.
20. The heat transfer surface as claimed in claim 1, wherein the
free ends of the tabs formed in one of the planar fin surfaces
extend through the openings formed in an adjacent planar fin
surface.
21. The heat transfer surface as claimed in claim 1, wherein said
heat transfer surface is arranged within enclosed tubular members
for the flow of a fluid therethrough.
22. The heat transfer surface as claimed in claim 1, wherein the
tabs are curved tabs having a curved edge raised out of the planar
fin surface forming the free end.
23. The heat transfer surface as claimed in claim 1, wherein the
tabs are rectangular tabs arranged with their longitudinal edges
generally parallel to the direction of incoming flow, the free end
corresponding to an end edge of the rectangular tab.
24. The heat transfer surface as claimed in claim 1, wherein the
tabs are rectangular tabs arranged with their longitudinal edges at
an angle to the direction of incoming flow, the free end
corresponding to a longitudinal edge and two end edges of the
rectangular tabs.
25. The heat transfer surface as claimed in claim 1, wherein the
tabs are split triangular tabs.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to and the benefit of U.S.
Provisional Patent Application No. 61/787,261, filed Mar. 15, 2013
under the title HEAT TRANSFER SURFACE WITH NESTED TABS. The content
of the above patent application is hereby expressly incorporated by
reference into the detailed description of the present
application.
TECHNICAL FIELD
[0002] The invention relates to heat exchangers, and in particular,
to heat transfer surfaces, such as fins, used to increase heat
transfer performance in heat exchangers.
BACKGROUND
[0003] In heat exchangers, particularly of the type used to heat or
cool fluids, it is common to use heat transfer surfaces, such as
fins, positioned between, adjacent to and/or inside fluid flow
passages in the heat exchanger to increase heat transfer
performance. Various types of heat transfer surfaces or fins are
known. One common type of heat transfer surface or fin is a
corrugated fin consisting of sinusoidal or rectangular corrugations
extending in rows along the length or width of the heat exchanger
plates or tubes, the heat transfer surface being positioned between
or adjacent to the heat exchanger tubes or stacked plates that make
up the heat exchanger. In order to further increase the heat
transfer performance of the heat transfer surface or fin, it is
known in the art to form a series of "slits" or "louvers" in the
planar surfaces of the heat transfer surfaces or fins. The slits or
louvers serve to disrupt boundary layer growth along the length of
the planar surfaces and increase mixing in the fluid flowing
over/through the heat transfer surface in an effort to increase
overall heat transfer performance of the heat exchanger.
[0004] While positioning a heat transfer surface or fin between the
tubular members or stacked plates of the heat exchanger increases
heat transfer performance by providing additional surface area for
heat transfer, heat transfer surfaces are also known to increase
pressure drop through the fluid channel in which the heat transfer
surface is located. Therefore while louvered fins and other heat
transfer surfaces with heat transfer augmenting features are known,
there is a continual need to provide improved heat transfer
surfaces that increase heat transfer performance without negatively
impacting pressure drop across the fin or heat transfer surface
whether it is positioned between the tubular members or within the
tubular members of a heat exchanger.
SUMMARY OF THE PRESENT DISCLOSURE
[0005] In accordance with an example embodiment of the present
disclosure, there is provided a heat transfer surface for a heat
exchanger comprising a corrugated member having a plurality of
parallel, spaced apart upper and lower ridges and planar fin
surfaces extending therebetween; each corrugation of said
corrugated member comprising either an upper or lower ridge and two
planar fin surfaces extending in the same direction from the
corresponding upper or lower ridge; the planar fin surfaces being
formed with a plurality of spaced apart tabs, each tab having an
attached base and a free end projecting out of the plane of the
corresponding planar fin surface; a plurality of openings formed in
the planar fin surfaces, the plurality of openings formed by the
tabs projecting out of the planar fin surface; the free ends of the
tabs formed in one of the planar fin surfaces extending into or
through the openings formed in an adjacent planar fin surface.
[0006] In accordance with another example embodiment of the present
disclosure there is provided a heat exchanger comprising a
plurality of stacked tubular members extending in spaced apart
generally parallel relationship; a first set of fluid flow passages
defined by said plurality of stacked tubular members; a second set
of fluid flow passages formed between adjacent tubular members; a
first manifold in communication with said first set of fluid flow
passages; a second manifold in communication with said first set of
fluid flow passages; and a plurality of heat transfer surfaces
disposed in said second set of fluid passages between adjacent
tubular members wherein each of the heat transfer surfaces
comprises a corrugated member having a plurality of parallel,
spaced apart upper and lower ridges and planar fin surfaces
extending therebetween; each corrugation of said corrugated member
comprising either an upper or lower ridge and two planar fin
surfaces extending in the same direction from the corresponding
upper or lower ridge; the planar fin surfaces being formed with a
plurality of spaced apart tabs, each tab having an attached base
and a free end projecting out of the plane of the corresponding
planar fin surface; a plurality of openings formed in the planar
fin surfaces, the plurality of openings formed by the tabs
projecting out of the planar fin surface; the free ends of the tabs
formed in one of the planar fin surfaces extending into the
openings formed in an adjacent planar fin surface.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Exemplary embodiments of the present disclosure will now be
described, by way of example, with reference to the accompanying
drawings, in which:
[0008] FIG. 1 is a perspective view of a heat exchanger
incorporating a heat transfer surface according to an exemplary
embodiment of the present disclosure;
[0009] FIG. 2 is a partial perspective view of a portion of the
heat transfer surface shown in FIG. 1;
[0010] FIG. 3A is a front elevation view of the heat transfer
surface shown in FIG. 2 showing nesting of the tab tips;
[0011] FIG. 3B is a front elevation view of the heat transfer
surface shown in FIG. 2 showing the nesting of the tab tips through
the corresponding openings formed in the adjacent planar fin
surface;
[0012] FIG. 4 is a detail perspective view of a portion of the heat
exchanger shown in FIG. 1;
[0013] FIG. 5 is a schematic drawing illustrating an alternate
embodiment of the heat transfer surface tab pattern according to
the present disclosure;
[0014] FIG. 6 is a schematic drawing illustrating another alternate
embodiment of the heat transfer surface tab pattern according to
the present disclosure;
[0015] FIG. 7 is a schematic cross-sectional drawing through a
portion of a planar fin surface of the heat transfer surface
illustrating another alternate embodiment of the heat transfer
surface according to the present disclosure;
[0016] FIG. 8 is a schematic drawing illustrating another alternate
embodiment of the heat transfer surface according to the present
disclosure;
[0017] FIG. 9 is a schematic cross-sectional drawing through a
portion of a planar fin surface of the heat transfer surface
illustrating another alternate embodiment of the heat transfer
surface according to the present disclosure;
[0018] FIG. 10 is a schematic cross-sectional drawing through a
portion of a planar fin surface of the heat transfer surface
illustrating another alternate embodiment of the heat transfer
surface according to the present disclosure;
[0019] FIG. 11 is a schematic cross-sectional drawing through a
portion of a planar fin surface illustrating yet another alternate
embodiment of the heat transfer surface according to the present
disclosure demonstrating the nesting of the tab tips when the heat
transfer augmenting tabs are bent in alternating directions along
the length of the fin surface;
[0020] FIGS. 12A-12E are schematic drawings illustrating various
other shapes of heat transfer augmenting tabs that can be
incorporated into the heat transfer surface according to the
present disclosure;
[0021] FIG. 13 is a detail schematic drawing illustrating the
counter-rotating vortices formed by the triangular tabs of the heat
transfer surface according to the present disclosure;
[0022] FIG. 14 is a graph showing the relationship between heat
transfer performance and fluid velocity for the heat transfer
surface according to the present disclosure as compared to other
known fin structures wherein the curve is representative of the
performance of the respective heat transfer surface or known fin
structure very near to its respective current manufacturing limit
for fin density;
[0023] FIG. 15 is a graph showing the relationship between pressure
drop and fluid velocity for the heat transfer surface according to
the present disclosure as compared to other known fin structures
wherein the curve is representative of the performance of the
respective heat transfer surface or known fin structure very near
to its respective current manufacturing limit for fin density;
[0024] FIG. 16 is a top perspective view of a portion of a planar
fin surface of a heat transfer surface with an angled saw-toothed
leading edge;
[0025] FIG. 17 is a side elevation view of the portion of the heat
transfer surface shown in FIG. 16 as viewed from the upper or lower
ridge of the corrugation;
[0026] FIG. 18 is a schematic cross-sectional drawing through a
portion of a planar fin surface of a heat transfer surface
illustrating another example embodiment of the heat transfer
surface according to the present disclosure;
[0027] FIG. 19 is a perspective view of a portion of a heat
exchanger or heat exchanger tube containing an example embodiment
of a heat transfer surface according to the present disclosure.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0028] Referring to FIG. 1, there is shown a heat exchanger
assembly 10 incorporating a heat transfer surface 12 according to
an exemplary embodiment of the present disclosure. The heat
exchanger assembly 10 includes a plurality of stacked tubular
members 14 that extend in spaced apart, generally parallel
relationship to each other. The plurality of stacked tubular
members 14, together define a first set of flow passages 16
therethrough for the flow of a first fluid through the heat
exchanger 10. A second set of fluid passages 18 is defined between
adjacent tubular members 14 for the flow of a second fluid, such as
air, through the heat exchanger 10. While tubular members 14 may
each be formed by a single tubular element, they may also be formed
by a pair of mating upper and lower plates and, therefore, may also
be referred to as plate pairs. The tubular members (or plate pairs)
14 are formed with raised embossments or boss portions 24 each
having an opening formed therein which serves as an inlet/outlet
opening for the flow of the first fluid through the tubular members
14. The boss portions 24 of one tubular member 14 aligning and
mating with the boss portions 24 on the adjacent tubular member 14
in the stack of tubular members to form inlet/outlet manifolds 26,
28 (only one of which is shown in the drawing). In some
embodiments, the boss portions 24 may both be positioned at one
longitudinal end of the tubular members 14 resulting in a generally
U-shaped flow path through the tubular member 14 while in other
embodiments one boss portion 24 may be located at respective ends
of the tubular members 14 thereby forming a heat exchanger 10 with
a manifold located at each of the respective ends. Furthermore, it
will be understood that while heat exchanger 10 is shown as a heat
exchanger formed of a plurality of stacked tubular members 14 with
integral inlet/outlet manifolds 26, 28, heat exchanger 10 may also
be formed by tubular members affixed to externally mounted
inlet/outlet headers to supply the stack of tubular members 14 with
fluid and to receive fluid from them. It will also be understood
that while the second set of fluid passages 18 are shown as being
open for the flow of a fluid such as freestream air therethrough,
the second set of fluid passages 18 could also be fed by a common
manifold for the inletting/discharging of a second fluid
therethrough. Accordingly, it will be understood that the present
disclosure is not intended to be limited to heat exchangers where
the second set of fluid passages 18 is open to freestream air as
would be understood in the art.
[0029] In the subject embodiment, heat transfer surfaces 12 are
attached to the outside surfaces of tubular members 14 and located
between the stacked, spaced apart tubular members 14 in the second
set of fluid passages 18 formed therebetween. Heat transfer surface
12 is in the form of a corrugated member having generally, parallel
spaced apart upper and lower ridges 30, 32 and generally planar fin
surfaces 34 extending between the upper and lower ridges 30, 32.
Each corrugation of the corrugated member is generally defined by
an upper or lower ridge 30, 32 and two planar surfaces 34 extending
in the same generally vertical direction from the upper or lower
ridge 30, 32. Each planar fin surface 34 also defines a first or
inner surface 33 and a second or outer surface 35, although whether
the first or second surface is considered an inner surface or an
outer surface depends on whether one is considering a corrugation
based on an upper ridge 30 with downwardly depending planar fin
surfaces 34 or a corrugation based on a lower ridge 32 with
upwardly extending planar fin surfaces 34. For the purpose of the
embodiments described in the present disclosure, reference is made
to the planar fin surface 34 defining an inner surface 33 and an
outer surface 35 with regard to a corrugation based on an upper
ridge 30, however, it will be understood that surfaces 33, 35 would
be reversed when considering a corrugation based on a lower ridge
32.
[0030] As shown in FIG. 3, the upper and lower ridges 30, 32 are
rounded with the planar fin surfaces 34 being generally upright or
vertical and parallel to each other. However, it will be understood
that the upper and lower ridges 30, 32 can also be generally flat
surfaces depending upon the particular embodiment of the heat
transfer surface 12 and the heat exchanger 10, and that the planar
fin surfaces 34 may also be formed so as to extend at an angle away
from a vertical axis through the corresponding upper or lower ridge
30, 32.
[0031] As shown in the drawings, the planar fin surfaces 34 are
formed with a series of projections in the form of delta wing tabs
or triangular tabs 36 that project or extend out of the surface of
the planar fin surface 34. As is generally understood in the art, a
"delta wing" refers to a triangular-shaped tab wherein the
triangular point or tip 38 is detached from and lifted out of the
planar fin surface 34 in which it is formed with the tip 38 being
oriented upstream from the attached base 40 of the tab 36. By
lifting the triangular tips 38 out of the plane of the planar fin
surface 34 to form an angle with said planar surface, a
corresponding opening 39 is formed in the planar fin surface
34.
[0032] In the subject exemplary embodiment shown primarily in FIGS.
2-4, the triangular tabs 36 are all positioned with their tips 38
pointed in the same, upstream direction. The triangular tabs 36 in
the heat transfer surface 12 are also formed so that all of the
tips 38 project or extend out of their respective planar fin
surface 34 in the same direction. More specifically, as shown most
clearly in FIG. 3, when the heat transfer surface 12 is viewed from
its front or leading edge 42 with respect to the direction of
incoming flow represented by arrow 41 in FIGS. 1 and 2, all of the
triangular tabs 36 are directed in the same general direction, i.e.
to the right in the specific exemplary embodiment illustrated in
the drawing. It will be understood, however, that the triangular
tabs 36 could also all be directed in the opposite direction, i.e.
towards the left, depending upon the particular
orientation/position of the heat transfer surface 12 and in other
embodiments could be directed in the same direction but at
different angles, or could be directed in different directions
depending upon the specific embodiment of the heat transfer surface
12. In the subject embodiment, when considering an individual
corrugation, it will be understood that the triangular tabs 36 on a
first of the two planar fin surfaces 34 that form the corrugation
project towards the inside surface 33 of the corresponding planar
fin surface 34 while the triangular tabs on the second of the two
planar fin surfaces 34 project towards the outside surface 35 of
the corresponding planar fin surface 34.
[0033] The triangular tabs 36 are bent or project out of the plane
of their respective planar fin surface 34 and are positioned at an
angle of attack to the incident flow (see arrow 41 in FIG. 1
representative of direction of fluid flow over the heat transfer
surface 12). By having the triangular tabs 36 project out of the
surface of the planar fin surface 34 with the tip 38 positioned at
an angle of attack to the incident flow, a pair of counter-rotating
vortices (shown schematically in FIG. 13) are formed within the
fluid flowing over the planar fin surface 34, which persist far
downstream along the length of the planar fin surface 34. By
introducing counter-rotating vortices within the fluid travelling
over the planar fin surfaces 34, boundary layer thickness within
the fluid is minimized which serves to increase the overall heat
transfer performance of the heat transfer surface 12.
[0034] As shown in FIGS. 2-4, the heat transfer surface 12 is also
preferably constructed so that the tips 38 of the triangular tabs
36 from one planar fin surface 34 extend into or are nested within
the openings 39 formed in the adjacent planar fin surface 34 by the
triangular tabs 36 formed therein. The tips 38 of the triangular
tabs 36 may also extend through the openings 39 in the adjacent
planar fin surface 34 so that the tips 38 project beyond the outer
surface 35 of the adjacent planar fin surface 34 as shown clearly
in FIG. 3B. The tips 38 may also simply nest within the
corresponding openings 39 in the adjacent planar fin surface 34 as
opposed to extending all the way through the openings 39 as shown,
for instance in the encircled areas 43 in FIG. 3A. The nesting of
the triangular tabs 36 between adjacent planar fin surfaces 34, as
shown primarily in FIGS. 3A and 3B, allows for increased fin
density within the heat transfer surface 12 since the planar fin
surfaces 34 can be positioned closer together. It has been found
that the nesting of the triangular tabs 36 appears to increase the
overall heat transfer performance without appearing to have an
adverse effect on pressure drop as is common in some known louvered
fin designs. Without taking advantage of the nesting of the tabs
36, it has been found that any performance increase in the heat
transfer surface 12 is limited by the fin density/spacing, the
number of tabs 36 provided, the size of the tabs 36 as well as the
angle of attack at which the tabs 36 are positioned with respect to
the incoming flow. While enhanced performance characteristics
relating to overall heat transfer performance and pressure drop
alone are desirable and appear to represent potential advantages
over known heat transfer surfaces with plain fin surfaces, the
increased fin density achievable with the subject heat transfer fin
12 due to the nesting of the triangular tabs 36 between adjacent
planar fin surfaces 34 has been found to potentially give rise to
improved heat transfer performance beyond what is typically found
with conventional, known louvered fins.
[0035] It has also been found that the nesting of the delta wing or
triangular tabs 36 may not interfere with or may not have an
adverse effect on formation of the flow patterns, e.g. the
formation of counter-rotating vortices, that appear to contribute
to potential heat transfer enhancement, which appears to indicate
that the increased fin density of the subject heat transfer surface
does not significantly decrease the overall effectiveness of the
fin as is sometimes found with other, known fins or heat transfer
surfaces. FIGS. 14 and 15 demonstrate findings relating to the
performance of the heat transfer surface 12 according to the
present disclosure as compared to known plain fin and louvered fin
structures where the curves are representative of the performance
of the respective heat transfer surface or known fin structure very
near to its respective manufacturing limit for fin density, the
subject heat transfer surface 12 being referred to as "delta wing
fin" in the attached graphic representations. As shown in FIGS. 14
and 15, the subject heat transfer surface 12 offers improved heat
transfer performance over both the known plain fin and the known
louvered fin structures for the same flow velocity while also
offering improved pressure drop as compared to the known louvered
fin structures each at their respective upper manufacturing limit
for fin density. Accordingly, based on the above-mentioned results,
it has been found that the heat transfer surface 12 according to
the present disclosure outperforms the known louvered fin structure
in both pressure drop and heat transfer with the louvered fin
structure at its furthest limit of attainable performance (i.e. at
its maximum fin density).
[0036] While the exemplary embodiment shown primarily in FIGS. 1-4
shows the heat transfer surface 12 being formed with three rows of
triangular tabs 36 that extend along the length of the planar fin
surface 34 with all of the triangular tabs 36 being arranged inline
with each other (i.e. one behind the other) with all of the
triangular tips 38 pointed in the same direction relative to the
incoming flow (i.e. uni-directional triangular tabs) as is shown
most clearly in FIGS. 2 and 3, it will be understood that the exact
number of rows of tabs will depend on the actual size of fin or
heat transfer surface being used based on the particular
application. For instance, certain fins, such as fins with a height
of 2.5-3.0 mm, may not accommodate three rows of triangular tabs 36
while other larger fins may be able to accommodate more than three
rows of triangular tabs 36. Accordingly, it will be understood that
the three rows of triangular tabs 36 shown in the drawings is
intended to be illustrative and not limiting to the heat transfer
surface 12 described herein. Various other arrangements of the
triangular tabs 36 are also contemplated within the scope of the
present disclosure as will be described in further detail
below.
[0037] Referring now to FIG. 5, there is shown another exemplary
embodiment of the heat transfer surface 12 according to the present
disclosure wherein the rows of triangular tabs 36 formed in the
planar fin surfaces 34 are arranged in a staggered pattern as
opposed to having all of the triangular tabs 36 arranged in line
with each other. In the staggered arrangement, the triangular tabs
34 in each row are still arranged one behind the other, although
the tabs 36 may be spaced farther apart from one another. In the
embodiment shown, the first or uppermost row of triangular tabs 36
is formed so that the first triangular tab 36' is positioned
generally at the leading edge 42 of the corresponding planar fin
surface 34, e.g. in a first position. The subsequent or middle row
of triangular tabs 36 is formed so that the first triangular tab
36'' in that row is set back from the leading edge 42 of the planar
fin surface 34 thereby creating a staggered pattern with respect to
the first row of tabs 36. The third or final row of triangular tabs
36 shown is formed so as to mimic the formation or positioning of
the first row of triangular tabs 36 with the first tab 36''' in the
third row being positioned generally at the leading edge 42 of the
planar fin surface 34. While the rows of triangular tabs 36 are
shown in their staggered arrangement, the triangular tabs 36 can
still be formed so as to nest within the openings 39 formed by the
corresponding triangular tabs 36 in the adjacent planar fin surface
34. Accordingly, increased fin density can still be achieved with
the triangular tabs 36 arranged in a staggered formation. While
only three rows of triangular tabs 36 have been illustrated, it
will be understood that the exact number of rows may vary depending
upon the size of the fin surface and/or the particular application
in which case the staggered pattern described above would repeat
over the surface of the fin.
[0038] Referring now to FIG. 6, there is shown another exemplary
embodiment of the heat transfer surface 12 according to the present
disclosure wherein the rows of triangular tabs 36 are formed in a
cascaded pattern along the length of the planar fin surfaces 34.
More specifically, in the cascaded arrangement, while the
triangular tabs 36 in each individual row are essentially arranged
in an in-line pattern (i.e. one behind the other), the spacing or
gap formed between each individual tab 36 is larger or increased as
compared to the first exemplary embodiment described above in
connection with FIGS. 1-4. As described above, the first or
uppermost row of triangular tabs 36 in the cascaded arrangement is
formed so that the first triangular tab 36' is positioned generally
at the leading edge 42, e.g. in a first position, of the
corresponding planar fin surface 34 with the remaining tabs 36
positioned at spaced apart intervals behind this first tab 36'
along the length of the planar fin surface 34. The subsequent or
middle row of triangular tabs 36 is formed so that the first
triangular tab 36'' in that row is set back from the leading edge
42 of the planar fin surface 34 by a predetermined distance so that
each tab 36 in the second row of triangular tabs 36 is positioned
slightly downstream from the corresponding triangular tab 36 in the
first row, with this pattern continuing along the length of the
planar fin surface 34. The third or final row of triangular tabs 36
shown in FIG. 6 is formed so that the first tab 36''' in the third
row is set back from the leading edge 42 of the planar fin surface
34 by another predetermined distance so that each tab 36 in the
third row is positioned slightly downstream from the corresponding
triangular tab 36 in the second or middle row with this pattern
continuing along the length of the planar fin surface 34. As
described above in connection with FIGS. 1-4, the tabs 36
(including tabs 36', 36'' and 36''') are all lifted out of the
plane of the planar fin surface so as to be positioned at an angle
of attack with respect to the directing of incoming flow. The tabs
36 on one planar fin surface 34 are all bent or directed towards
either the inside surface or outside surface of the planar fin
surface 34 in order to achieve the nesting effect between adjacent
planar fin surfaces 34. Accordingly, increased fin density can
still be achieved with the triangular tabs 36 arranged in the
described cascaded formation. Furthermore, it will be understood
that the cascading pattern may continue beyond three rows of
triangular tabs 36 and that the actual number of rows will vary
depending upon the size of the planar fin surface 34 as well as the
particular design and/or application of the heat transfer surface
12. As well, it will be understood that the spacing between the
rows of triangular tabs 36 is not necessarily uniform and that
distance between subsequent tabs 36 in a row may vary as shown, for
example, in the first row of tabs 36 of FIG. 6 where the third tab
36 in the first row is spaced farther apart from the other tabs 36
in the same row. The non-uniform spacing between the tabs may be
used to form varying patterns over the planar fin surface 34.
[0039] Referring now to FIG. 7, there is shown yet another
exemplary embodiment of the heat transfer surface 12 according to
the present disclosure. In the subject embodiment, the triangular
tabs 36 are combined with flow accelerating features 46 arranged
behind each triangular tab 36 in an alternating pattern along the
length of the planar fin surface 34. In the subject embodiment, the
flow accelerating features 46 are in the form of "bumps" or rounded
protrusions that project out of the surface of the planar fin
surface 34, although any suitable flow accelerating feature is
contemplated within the scope of the present disclosure. These
features serve to accelerate the flow in the direction parallel to
the vortices, hence increasing the vorticity. It will be understood
that while the embodiment shown in FIG. 7 shows the triangular tabs
36 and the flow accelerating feature 46 protruding in the same
direction out of the plane of planar fin surface 34, alternate
embodiments may include flow accelerating features 34 protruding
from alternate sides of the planar fin surface 34 and that the
specific pattern may vary. However, it will be understood that all
adjacent planar fin surfaces 34 would have the same pattern of tabs
36 and flow accelerating features 46 to provide for the nesting
relationship between adjacent planar fin surfaces 34.
[0040] Referring now to FIG. 8 there is shown another exemplary
embodiment of the heat transfer surface 12 according to the present
disclosure. As shown, in addition to having the triangular tabs 36
formed in the planar fin surfaces 34 of the corrugated heat
transfer surface 34, it is also contemplated to modify the leading
edge 42 of the fin or heat transfer surface 12 to incorporate
triangular tabs 48 into the leading edge 42 of the heat transfer
surface 12 in the form of a "saw-toothed" leading edge 42. The
triangular tabs 48 formed in the leading edge 42 can be arranged so
as to extend co-planar with each planar fin surface 34, as shown in
FIG. 8, or can be bent outward (or inward) with respect to the
corresponding planar fin surface 34 so as to be positioned at an
angle of attack with respect to the incoming fluid flow as shown,
for example, in FIGS. 16 and 17.
[0041] Referring now to FIG. 9, there is shown another exemplary
embodiment of the heat transfer surface 12 according to the present
disclosure. In all of the embodiments described above the
triangular tabs 36 have been shown as being arranged generally
in-line with each other (i.e. one behind the other in each row of
tabs along the length of the planar fin surface) and
uni-directional (i.e. all triangular tabs point in the same
direction relative to the flow direction on the planar fin surface
14). However, in other embodiments the triangular tabs 36 may be
arranged so as to be "bi-directional" as shown, for example in FIG.
9. More specifically, the triangular tabs 36 in the planar fin
surfaces 34 are formed so that the tabs 36A found in the first half
of the planar fin surface 34, i.e. from the leading edge 42 of the
heat transfer surface to the midway point of the heat transfer
surface along the length of the corrugations, are arranged with
their triangular tips all generally pointing in the direction of
the incoming flow, although it will be understood that the tabs 36A
themselves are arranged at an angle of attack with respect to the
incoming flow. The triangular tabs 36B formed over the second half
of the planar fin surface 34, i.e. from the midway point of the
heat transfer surface along the length of the corrugations to the
end edge are arranged so as to point in the opposite direction to
the tabs 36A over the first half of the planar fin surface 34. More
specifically, triangular tabs 36B are arranged so that the attached
base 40 of the tab 36B is arranged upstream with respect to the
triangular tip 38 and with respect to the direction of the incoming
fluid flow. By having the triangular tabs 36A, 36B arranged in a
bi-directional pattern over the planar fin surfaces 34, the heat
transfer surface 12 is bi-directional since it can be used in
either direction and have triangular tabs 36 with tips 38 arranged
at an angle of attack with respect to the incoming flow.
[0042] FIG. 18 illustrates another embodiment of the heat transfer
surface 12 similar to that described above in connection with FIG.
9. As shown, the heat transfer surface 12 can also be formed so as
to have bi-directional triangular tabs 36A, 36B arranged in a
different pattern than simply having half of the planar fin surface
formed with delta wing or triangular tabs 36A with the triangular
tips arranged upstream with respect to the attached base 40 with
respect to the direction of incoming flow and with oppositely
formed tabs 36B over the remaining half of the planar fin surface
34. More specifically, the triangular tabs 36 may be arranged in
repeating and/or alternating patterns having a certain number of
triangular tabs 36A arranged with the tips 38 pointing upstream
followed by a certain number of triangular tabs 36B arranged with
the tips 38 pointing downstream with respect to the incoming flow
followed by another series of triangular tabs 36A arranged with
their tips 38 pointing upstream. While FIG. 18 shows a section of a
planar fin surface 34 of a heat transfer surface 12 with a
repeating pattern of two upstream-pointing triangular tabs 36A
followed by two downstream-pointing triangular tabs 36B followed by
two upstream-pointing tabs 36A followed by two downstream-pointing
tabs 36B, it will be understood that the exact number of tabs 36A,
36B can be varied and/or can be different from each other depending
upon the specific application and/or design of the particular heat
transfer surface 12. Accordingly, it will be understood that the
embodiment shown in FIG. 18 is intended to be illustrative and not
limiting. For instance, while the planar fin surface 34 may be
provided with some triangular tabs 36A pointing upstream and some
triangular tabs 36B pointing downstream, the tabs 36 do not
necessarily need to be arranged in a repeating pattern and that
various groupings of tabs 36A, 36B can be formed in the planar fin
surface 34 over the length thereof. In addition to having the
triangular tabs 36A, 36B arranged bi-directionally, the size and
angle of attack of the tabs 36 may also be varied along the length
of the planar fin surfaces 34 as shown schematically in FIG.
10.
[0043] Referring now to FIG. 11 there is shown another exemplary
embodiment of the heat transfer surface 12 according to the present
disclosure. In this embodiment, rather than having all of the
triangular tabs 36 in one planar fin surface 34 being bent in the
same or a single direction out of the plane of the planar fin
surface 34 the triangular tabs 36 can also be formed so that the
tabs 36 are bent in alternating directions as shown schematically
in FIG. 11. More specifically, in this particular embodiment each
row of triangular tabs 36 formed along the length of the planar fin
surface 34 comprises a first set of tabs 36C that are bent or
lifted out of the plane of the planar fin surface 34 in a first
direction (i.e. towards either the inside surface 33 or outside
surface 35 of the planar fin surface 34) that are spaced apart
along the length of the planar fin surface. A second set of tabs
36D are arranged in between the first set of tabs 36C so that the
first and second set of tabs 36C, 36D form an alternating pattern
along the length of the planar fin surface 34, the second set of
tabs 36D being bent or lifted out of the planar fin surface 34 in a
direction opposite to that of the first set of tabs 36C. The same
alternating pattern of tabs 36C, 36D is formed in the adjacent
planar fin surfaces 34 so that the tabs 36C, 36D can nest within
the corresponding opening formed in the adjacent planar fin surface
34 as in the previously described embodiment. Accordingly, the
increased fin density can be achieved with the triangular tabs 36C,
36D being arranged in the alternating pattern.
[0044] While the exemplary embodiments of the subject heat transfer
surface 12 have all been described in relation to triangular or
delta wing tabs 36, it will be understood that other shapes of tabs
are also contemplated with the scope of the present disclosure.
More specifically, curved tabs 52 may also be formed in the planar
fin surfaces 34 of the heat transfer surface 12 in any of the
various patterns described above (i.e. staggered arrangement;
cascaded arrangement; bi-directional arrangement; alternating
directions, etc). The curved tabs 52 are formed in a similar
fashion to the triangular tabs 36 described above with their
rounded or curved edge 53 lifted out of the plane of the planar fin
surface 34 and arranged at an angle of attack to the incoming flow
41 upstream of the attached base 54. While curved tabs 52 may not
necessarily form the same counter-rotating vortices in the fluid
flowing over the heat transfer surface 12 as discussed above in
connection with the triangular or delta wing tabs 36, the curved
tabs 52 have also been found to create vortices in the fluid flow
that serve to disrupt boundary layer growth over the surface of the
fin 12 which has been found to contribute to overall increased heat
transfer performance. Curved tabs 52 can also be nested within the
openings formed by the corresponding curved tabs 52 formed in the
adjacent planar fin surface 34 in order to achieve the increased
fin density which also serves to increase overall heat transfer
performance.
[0045] Delta winglets 56 and/or split triangular tabs 58 are
another variation of tabs that can be incorporated into the subject
heat transfer surface 12. Delta winglets 56 are triangular in shape
but rather than having the tip 38 lifted out of the planar fin
surface 34 as in the previously described embodiments, the
triangular tab 56 is lifted out of the plane of the planar fin
surface 34 along one of its edges 57 and along the shorter base
side 55 of the triangular tab with the opposite edge 59 serving as
the attached base as shown in FIG. 12B. Split triangular tabs 58
are formed by splitting or cutting a triangular tab down the middle
as shown in FIG. 12C and lifting the cut or split edge 60 and
shorter base edge 55 of the split triangular tab out of the plane
of the planar fin surface 34 with the opposed edge 61 of the split
triangular tab 58 serving as the attached base. Accordingly, the
split triangular tabs 58 essentially comprise two delta winglets
56. Once again, the delta winglets 56 and the split triangular tabs
58 can be arranged in any of the various patterns described above
and are also capable of nesting within the openings formed in the
adjacent planar fin surface 34 so as to achieve increased fin
density for the heat transfer surface 12.
[0046] Rectangular tabs 62 that are lifted out of the planar fin
surface 34 so that their tips 64 are arranged at an angle to the
incident flow as shown schematically, for example, in FIG. 12D are
also contemplated within the scope of the present disclosure. The
rectangular tabs 62 can be arranged so as to have one free end 64
of the rectangular tab 62 lifted out of the plane of the planar fin
surface 34 with the end 64 being upstream of the attached base 66.
Alternatively, the rectangular tabs 62 can be arranged so as to
have one of the longitudinal edges 68 of the rectangular tab 62
serve as the attached base with the opposed longitudinal edge 68
and shorter end edges 64 being lifted out of the plane of the
planar fin surface 34 as shown schematically in FIG. 12E. Once
again, rectangular tabs 62 can be arranged in any of the various
patterns described above and are also capable of nesting within the
openings formed in the adjacent planar fin surface 34 so as to
achieve increased fin density for the heat transfer surface 12.
[0047] The various embodiments of the heat transfer surface 12
described above appear to provide for improved overall heat
transfer performance of a heat exchanger while offering a lower
pressure drop across the heat transfer surface 12 as compared to
the more traditional louvered fin. By lowering the pressure drop
across the fin or heat transfer surface 12 in addition to
demonstrating increased heat transfer performance, heat transfer
surface 12 appears to be potentially well-suited for charge-air
cooler (CAC) applications. More specifically, it appears that by
reducing pressure drop or pressure losses across the heat transfer
surface 12, the required turbocharger pressure ratio (or
supercharger pressure) can also be reduced which in turn appears to
reduce heating due to compression of the air flowing through the
device which further reduces the load on the CAC. These
characteristics are often highly desirable for many automotive
intake systems where any improvement in efficiency is often found
to be highly desirable. While the heat transfer surface 12
described herein may be well-suited for CAC applications, it will
be understood that the subject heat transfer surface 12 is not
limited to CAC applications and is also not necessarily limited to
use as an air-side fin. For instance, heat transfer surface 12 may
also be used inside tubular fluid flow channels for the flow of a
liquid therethrough.
[0048] While the various embodiments of the heat transfer surface
12 have primarily been described in relation to use between the
spaced apart tubular members 14 of a heat exchanger, e.g. for use
as an air-side fin, it will be understood that the same heat
transfer surface 12 can also be appropriately dimensioned for use
within the tubular members 14, as shown for instance in FIG. 19, in
order to increase turbulence and/or disrupt boundary layer growth
within the fluid flowing through flow passages 16. While tubular
member 14 is shown as a being formed by a one-piece tubular member,
it will be understood that it may also be formed by mating plate
pairs. As well, while tubular member 14 is shown as having opposed,
open ends for the flow of a fluid therethrough, it will be
understood that the tubular member may be formed with a closed or
sealed peripheral edge, the flow passage 16 being fed by means of
fluid inlet/outlet openings formed therein that communicate with
corresponding fluid inlet/outlet openings in adjacent tubular
members 14 forming the heat exchanger.
[0049] While various exemplary embodiments of the heat transfer
surface 12 have been described and shown in the drawings, it will
be understood that certain adaptations and modifications of the
described exemplary embodiments can be made as construed within the
scope of the present disclosure. Therefore, the above discussed
embodiments are considered to be illustrative and not
restrictive.
* * * * *